- Certain heart medicines (flecainide or propafenone); antihistamines (astemizole and terfenadine); rifampin; ergot derivatives (dihydroergotamine, ergonovine, ergotamine, or methylergonovine); intestinal agents (cisapride); herbal products (St. John's wort); lovastatin or simvastatin; neuroleptics (pimozide); and sedatives/hypnotics (midazolam or triazolam)